1. Field
One or more embodiments relate to a method and apparatus for encoding or decoding an audio signal with music and speech characteristics, and more particularly, to a method and apparatus for efficiently encoding and decoding such an audio signal by using a small number of bits.
2. Description of the Related Art
When coding audio, one of a plurality of various coding modes may be selected to code an input signal by analyzing the characteristic of the input signal. For example, a frequency-domain coding mode such as an advanced audio codec (AAC) method or a time-domain coding mode such as a code excited linear prediction (CELP) method may be selected to code the input signal. Conventionally, if the characteristic of the input signal is determined to more closely represent characteristics of music, the frequency-domain coding mode is selected to code the input signal. If the characteristic of the input signal is determined to more closely represent characteristics of speech, the time-domain coding mode is selected to code the input signal.
Here, in such an operation, when a coding mode of an input signal is selected, the characteristics of signals in previous frames may be stored and the coding mode of a current frame may be determined based on the stored characteristics of the previous frames as well as characteristic of the current frame. However, in such an approach, both the number of times that a signal coding mode changes, and any corresponding delay caused by such changes, should be reduced.